New catalysts and new processes that enhance reactions between hydrogen and organic materials will be of great benefit to many industries. One industry that clearly exemplifies some of those benefits is the energy industry. The expanding need for energy in North America, combined with the depletion of known crude oil reserves, has created a serious need for the development of alternatives to crude oil as an energy source. One of the most abundant energy sources, particularly in the United States, is coal. Estimates have been made which indicate that the United States has enough coal to satisfy its energy needs for the next two hundred years, while Canada has over 330 billion barrels of oil bound in the bitumen tar sands of Alberta.
Unfortunately both coal and tar sands (bitumen) are solids, or nearly solids, at ambient temperatures. They have a high carbon content but hydrogen contents of typically only 5% to 9%. In comparison with fuels that are liquid at ambient temperatures, they are inconvenient to handle and unsuited to some applications. Most notably they cannot be used directly to fuel the internal combustion engines and turbines that dominate transportation infrastructures worldwide. Transportation fuels are derived overwhelmingly from crude oil, which has about twice the hydrogen content of coal. The hydrogen content of typical transportation fuels varies from approximately 12.5% in some gasolines to approximately 14.5% in aviation turbine fuels. For coal or bitumen to replace them, they must be converted to liquids with similar hydrogen content.
Liquid fuels have long been produced from coal and bitumen. In general, current processes achieve this by either removing carbon (through pyrolysis or coking) or adding hydrogen (through liquefaction or hydrogenation). Since a comparison of the relative costs of crude oil and these other hydrocarbons are favorable, the commercial viability of such hydrocarbons as transportation fuels depends on the overall economics of the conversion processes. Recent estimates (1990) indicate that two-stage conversion of coal to liquids has a product cost of about $38 per barrel and that the improved quality of the liquids makes them equivalent to oil costing $33 per barrel. Environmental costs are also high. Converting coal to transportation fuels reportedly results in 7–10 times as much CO2 emissions as converting crude oil. This increase in CO2 emissions at the processing stage has the effect of raising overall CO2 emissions from the transportation sector by approximately 50%, compared with transport based on conventional, refined petroleum products.
Incremental improvements to the established process steps are unlikely to decrease processing costs sufficiently to achieve a competitive price of $25 per barrel or to significantly reduce CO2 emissions.
Structurally, bituminous coal typically consists of mono-cyclic and condensed aromatic rings, varying in size from a single ring to perhaps four or five rings, linked to each other by connecting bridges which are typically short aliphatic chains or etheric linkages. Generally, coal liquefaction and bitumen hydrogenation processes occur at temperatures exceeding 400° C. by rupturing the connecting bridges to form free radicals. The free radicals are then capped by a small entity such as hydrogen. If the free radicals are not capped, they will combine in condensation or polymerization reactions to produce large structures that are solid at room temperature.
The direct coal liquefaction technologies produce large amounts of hydrocarbon gases, the ratio of liquids to hydrocarbon gasses usually being of the order of 3/1 to 4/1. Residence times of materials (reactants plus products) in the temperature zone above 350° C. are characteristically between 15 minutes and 1 hour. Such long exposure of the primary liquid molecules to temperatures above 350° C. results in extensive thermal cracking, yielding hydrocarbon gasses. Since more than half of the gas formed is methane, this cracking results in a large consumption of hydrogen and significantly increases the cost of production.
Recent studies described by Wiser et al, in U.S. Pat. No. 5,783,065 have reportedly demonstrated an improved simultaneous process for direct liquefaction and hydrogenation in the presence of a catalyst that generates a high proportion of liquid hydrocarbon product. Part of the benefit taught by the Wiser process is claimed to be the shortening of reaction times, thereby limiting hydrocracking and thus producing a higher quantity of liquid product.
It would be beneficial if catalytic hydrogenation of organic materials could be accomplished under conditions where the organic materials were not exposed to temperatures in excess to those required for the desired reaction for excess periods of time.
Whatever the organic feedstock, it can be generally stated that the efficiency of the hydrogenation process is enhanced by employing materials and methods whereby the molecules of feedstock are brought together with hydrogen, under temperature and pressure conditions required to cause the substances to react in the presence of a fresh catalytically active surface. In other words the heat, hydrogen, and organic material must all come together at the same time on the surface of the catalyst. Processes that enhance the probability of these conditions occurring simultaneously would be generally anticipated to improve efficiency. The present inventor has discovered that these and other benefits may be realized by the application of a catalyst comprised of intercalation compounds on a support structure.
Intercalation compounds may be conceptualized as being comprised of two components, a host intercalated material (M), and a visiting insertion material or intercalate (X). The host intercalation materials may be defined as elements, naturally occurring intermetallic compounds, or synthetic structures that allow the reversible insertion of ions, atoms, or molecules of another material (i.e. the intercalate) within spaces in the host structure. The bonding of the intercalated material with the intercalate does not change the chemical properties of the intercalate. In other words lithium intercalated into a material remains essentially lithium—hydrogen intercalated within a host remains essentially hydrogen and each can typically be repeatedly withdrawn and reinserted without damage to the host. It is often desirable that the host material is dimensionally stable during repeated intercalations and de-intercalations.
Alkali metal intercalated compounds are well known commercially produced materials. They are particularly well recognized with respect to their use as both anode and cathode materials in lithium batteries. Processes for intercalating alkali metals do not form a part of the present invention and any known methods for intercalation may be employed. Intercalation methods may be exemplified by U.S. Pat. No. 3,933,688, to Dines and U.S. Pat. No. 4,040,917 to Whittingham, and many other examples known to those skilled in the art.
U.S. Pat. No. 4,822,590 and U.S. Pat. No. 5,072,886, to Morrison et al., both of which are incorporated in the present application by reference, discloses how layered or porous materials intercalated with alkali metals may be separated or fractured into higher surface area materials by immersing the alkali metal intercalated material in a liquid that generates a gas upon reaction with the alkali metal. It is suggested that the separated or fractured materials may be useful in catalysis. However, the patents do not teach the benefit that may be achieved by employing the heat and hydrogen and fresh catalytically active surfaces generated by said reaction to enhance the hydrogenation of organic material.